INCIDENCE, SURVIVAL AND BIOCONTROL OF PSYCHROTROPHIC BACILLUS CEREUS AND ITS POTENTIAL FOR TOXIN PRODUCTION IN MILK AND TALLAGA CHEESE
 
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Pol. J. Food Nutr. Sci. 2006;56(4):419–425
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ABSTRACT
The incidence of Bacillus cereus, psychrotrophic character and the ability of isolates to produce haemolysin were investigated to evaluate their health potential in some dairy products. In total 125 samples (skim milk powder, white soft cheese, processed cheese, Kareish cheese and rice with milk) were analysed. Of these (39.2%) contained B. cereus. The viability of (reference and isolated strains) B. cereus and toxin production in sterilized milk was examined during storage at 10°C for 7 days. The two tested strains, when inoculated in milk with 105 cfu/mL, were shown to be capable of producing toxin at the end of the storage period. The antimicrobial activity of 7 strains of lactic acid bacteria against B. cereus was tested to select the effective starter to control the pathogen. Lactobacillus reuteri followed by Lb. rhamnosus were the most effective probiotic cultures. The choice was a mixed culture of Lactococcus lactis ssp. diacetylactis as a starter culture and Lb. rhamnosus as a probiotic culture (1:1) to use in manufacture of Tallaga cheese. The use of this starter resulted in reduction of viable count of B. cereus and so, no toxin was detected in these cheeses. In contrast, in the control cheese (inoculated with 105 cfu isolated strain of B. cereus), the viable counts of B. cereus increased and released detectable amount of enterotoxin at the end of refrigerated storage.
ISSN:1230-0322